This invention relates to designs and methods for preventing, stopping or slowing myopia progression.
Myopia, also known as short-sightedness, is a refractive condition wherein the overall power of the eye is too high, or too strong, causing light from distant objects to focus in front of the retina. This is perceived by the viewer as blurring of distant objects, with the amount of blurring being related to the severity of the myopia. This condition is often first seen in childhood, and usually noticed at school age. A progression, or increase, in the severity of myopia, is usually seen in myopic cases until young adulthood.
U.S. Pat. No. 6,045,578 proposes methods of using on-axis longitudinal spherical aberration (LSA) in contact lens designs to attempt to halt myopia progression. The design approach suggested does not appear to address specific wavefront/refractive power characteristics of the individual eye/or group average data or changes in pupil size associated with close work.
U.S. Pat. No. 7,025,460 proposes methods of altering field curvature (off-axis focal point variation) to try to halt myopia progression. The mathematics behind this approach uses “extended conics” where the simple conic equations have even ordered polynomial terms added to them. These conic and polynomial terms are processed so that the contact lens surface shape of the proposed design produces the required amount of field curvature.
US 2003/0058404 and US 2008/0309882 proposes a method of measuring the wavefront of the eye and correcting the wavefront of the eye with a customized correction to slow myopia progression. Pupil size changes associated with near tasks were not an aspect of the design process.
EP 1853961 proposes the measurement of the wavefront before and after near work. The changes in wavefront aberrations are then corrected with a custom contact lens. Group or population data to create a design to control eye growth are not included.
“Orthokeratology Alters Aberrations of The Eye”, Optometry and Vision Science, May 2009. The article discusses higher order aberrations of the eye associated with orthokeratology.
A more complete approach to slowing or stopping myopia progression is still desired. This is addressed in this specification.